Effectiveness and Safety of Hair Growth Formulation Containing Tectona grandis L.f (Teak) Leaf Extract: A Randomized, Double-Blind, Placebo-Controlled Study on Males with Androgenic Alopecia

Abstract

Background: Androgenic alopecia (AGA) is commonly known as male patterned baldness. A high level of dihydrotestosterone (DHT) plays a significant role in AGA development. Inhibition of the enzyme steroid 5-alpha reductase (S5AR), responsible for converting testosterone into DHT, has been shown to delay the progression of AGA. Teak (Tectona grandis L.f) leaf extract exhibited a potent S5AR inhibitory activity. To prove the effectiveness and safety of teak leaf extract as a hair growth promotor, a double-blind, randomized placebo-controlled trial was conducted.

Methods: Eighty-one AGA subjects were randomly assigned to receive either a hair tonic containing 1% teak leaf extract (HT-teak), 5%minoxidil (positive control), or a placebo administered twice daily, for 24 weeks. Efficacy was assessed through target area hair count (TAHC), anagen-to-telogen ratio (A/T), hair shedding every 4 weeks, and patients' subjective assessments of hair regrowth were assessed at the end of the experiment. Data was analyzed using repeated measure ANOVA.

Results: Both the HT-teak and minoxidil groups exhibited a significant increase in TAHC and A/T, along with a decrease in hair shedding compared to baseline values. Conversely, the placebo group showed no observable signs of hair regrowth. Furthermore, the HT-teak group reported the highest satisfaction scores, and there were no indications of skin irritation or systemic effects on sexual dysfunction and palpitation after 24 weeks of HT-teak application.

Conclusion: Teak leaf extract, as incorporated in HT-teak, demonstrates potential as an alternative mild hair growth promoter for individuals with AGA, offering both efficacy and safety.

Trial registration: This study was retrospectively registered on International Standard Randomised Controlled Trial Number (ISRCTN.com); ISRCTN24541842 (registered on January 8, 2024).

Keywords: 5-alpha reductase inhibitor; androgenic alopecia; clinical trial; hair growth; teak; tectona grandis l.f.

Figure 1.

Flow diagram illustrating the subject enrollment and study evaluation protocol.

Figure 2.

Example trichoScan images taken from the target area of the scalp (20-fold magnification), comparing baseline and week 24 from the HT-teak group. The hair types are characterized by trichoscopy software. The upper images show hair characterized by length: green indicates anagen hair, and red indicates telogen hair. The lower images show hair characterized by thickness: blue indicates terminal hair, and yellow indicates vellus hair.

Figure 3.

The representative vertex area photographs of subjects who applied minoxidil, HT-teak, or placebo, at day0 (baseline) and week24. Two additional representative vertex area photographs from each treatment group were provided in the supplementary data.